Objectives of this project are to gain indepth understanding of demyelinating optic neuritis in humans through an experimental animal model. The pathology of human optic neuritis will be compared with the experimental optic neuritis produced in guinea pigs. In the experimental optic neuritis significance of blood optic nerve barrier in the development of demyelination will be evaluated. The acute and chronic optic neuritis are produced by systemic sensitization with central myelin in complete Freunds' adjuvant in guinea pigs. The localized optic neuritis will be produced by retrobulbar injection of synsitized lymphocytes. Sequential light and electron microscopic studies on the experimental material will be performed to detect pathogenesis of demyelination. The axonal function and blood optic nerve barrier studies will be performed by autoradiography grain counting technique and by injecting horse-radish peroxidase. The sites of demyelination as well as the altered blood optic nerve barrier foci will be examined for deposits of antimyelin antibodies by immunofluorescent and immunoperoxidase techniques.